What to Look for in a Home Extension Builder in Melbourne
Melbourne home extensions - rear ground-floor extensions, first-floor additions, side infills - are more technically complex than new builds because they integrate with existing structure. Cost band $180,000-$650,000 in 2026 depending on size and complexity.
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VBA class
DBU
Domestic Builder Unlimited
Cost band
$180k-$650k
2026 mid-market to premium
Duration
5-9 months
contract to Occupancy Permit
Framework
Clause 54
ResCode single-dwelling extensions
The vetting checklist that applies to every Melbourne specialist
BuildPilot does not yet match Melbourne builders. Until we do, this is the vetting method we would use ourselves. The first five checks below are specialist-specific; the rest are the core VBA + VMIA + ASIC checks that apply to every domestic builder working in Victoria.
- Ask their approach to existing-foundation integration - matching new footings to existing footings across a stepped detail
- Ask for photos of the roof-line junction between original and extension - how they meet the two roofs and manage the gutter/box-gutter
- Ask their track record on ResCode Clause 54 (single dwelling) extensions - overshadowing and overlooking rules still apply
- Ask about existing-structure protection - how they handle temporary weatherproofing during the demolition-to-lockup phase
- Verify current VBA registration and category on the public register at vba.vic.gov.au/practitioners/register
- Verify no active or recent disciplinary decisions on the VBA disciplinary decisions list
- Confirm Domestic Building Insurance (DBI) will be issued in the builder's name for your contract price under VMIA (all residential work over $16,000)
- Search the ABN on abr.business.gov.au - name, GST status, date of registration
- Confirm the entity is not under external administration on the ASIC register
The ResCode setback gotcha
A home extension is judged against the same ResCode Standards as a new build. Rear ground-floor extensions typically pass; first-floor additions frequently fail. The most common Planning refusal reason: overshadowing the neighbour's north-facing living window on 22 September under Clause 54.04-3, or overlooking within 9m under Clause 54.04-6. A good extension builder catches these at concept and redesigns before Planning lodgement.
The four red flags that end the conversation
These four signals correlate strongly with builders who have failed or entered administration in Victoria in the last three years. Any of them = walk away.
- Requested deposit exceeds 10% of contract value (Victorian DBC Act caps deposits at 5%)
- Vague or evasive answer on DBI eligibility for your specific contract price
- Refusal to name the Registered Building Surveyor or to let you speak to them independently
- Aggressive time-limited discount contingent on paying deposit before you have read the contract
In this episode we discuss the impact of making design or structural changes to your floorplan. Join us as we explain why different builders have different levels of allowable changes, what some of the more acceptable (or safer) changes are vs some of the more risky ones, and we finish off with our advice to you when considering or discussing structural changes with your builder.
Watch full episodeFrequently asked
Can I extend during Occupancy?+
Yes but disruptive. Most Melbourne extensions have 4-6 weeks of internal disruption. Some clients rent locally for the disruption period, some stay in the "other half" of the house behind temporary weatherproofing. Cost of interim accommodation is usually $8,000-$15,000.
Is a first-floor addition harder than a rear extension?+
Usually yes. First-floor additions load the existing ground-floor structure with new dead and live load. Engineering upgrade to existing footings/columns is common. Adds $30-70k to a first-floor addition budget.
How is extension pricing different from new-build pricing?+
Per-m² extension pricing runs 20-40% higher than equivalent new build. Reasons: integration complexity, site access constraint, existing-structure protection, and non-standard trade sequence.
Do extensions need DBI?+
Yes for any residential work over $16,000 - which covers all substantial extensions.
Note: the stories below are Adelaide-based clients - the underlying builder-matching process is identical for Melbourne buyers.
How our process runs - real client stories
Federuzzi Development
Two double-garage homes squeezed onto an odd-shaped subdivision block in Ingle Farm, with the equity earmarked to fund the next development.
Read the case studySterai Residence
A practical, well-planned knockdown rebuild on a tricky triangular block in Ingle Farm.
Read the case studyBuilding in Adelaide instead?
Read our Adelaide equivalent